Viral respiratory tract infections lead to the exacerbation of a number of respiratory diseases. In fact, viral respiratory tract infections are responsible for 85% of asthma exacerbations (Johnston et al., BMJ, 1995; 310: 1225-8; Nicholson et al., BMJ, 1993; 307: 982-6), including the most severe requiring hospitalisation (Johnston et al., Am. J. Respir. Crit. Care Med. 1996; 154: 654-660). It is of concern that viral infections can trigger severe asthma exacerbations even when there is good asthma control by compliant patients taking optimal doses of inhaled corticosteroids (Reddel et al., Lancet, 1999; 353: 364-369). The most common pathogen associated with asthma exacerbations is rhinovirus. Infection with rhinovirus leads to the release of inflammatory mediators (Teran et al., Am. J. Respir. Crit. Care Med. 1997; 155: 1362-1366) and increased bronchial responsiveness (Grunberg et al., Am. J. Respir. Crit. Care Med. 1997; 156: 609-616).
Subjects with asthma do not appear to be more susceptible in acquiring viral respiratory tract infections but they do have more severe lower respiratory tract symptoms (Come et al., Lancet, 2002; 359: 831-834). Although rhinovirus is known to infect bronchial epithelial cells (Gern et al., Am. J. Respir. Crit. Care Med. 1997; 155: 1159-1161) and has been isolated from the lower airway (Papadopoulos et al., J. Infect. Dis., 2000; 1821: 1875-1884; Gern et al., Am. J. Respir. Crit. Care Med. 1997; 155: 1159-1161), the reasons why the asthmatic lower respiratory tract is more prone to the effects of infection with rhinovirus are unclear. It is therefore necessary to determine why asthmatic bronchial epithelial cells have an abnormal response(s) to virus infection that causes increased viral replication and shedding leading to prolonged and augmented pro-inflammatory responses and associated exacerbation of asthma symptoms. It is also necessary to provide treatments for virally-induced exacerbations of asthma.
Surprisingly, it has been found that asthmatic bronchial cells are abnormal in their response to viral infection leading to increased virion production compared to healthy normal controls. This is despite the fact that both asthmatic and healthy cells mount an early inflammatory response to infection. It has also been shown that asthmatic cells are more resistant to early apoptosis following infection and have a deficient type I interferon response. This early apoptotic response is a key protective mechanism since inhibition of apoptosis in healthy control cells leads to enhanced viral yield. Therefore the increased virion production by asthmatic bronchial epithelial cells is associated with the ability of the cells to bypass apoptosis. Furthermore, it has been found that induction of apoptosis in asthmatic bronchial epithelial cells using IFN-β causes a significant reduction in infectious virion production. The invention therefore relates to the treatment of virally-induced exacerbations of asthma using an apoptosis-inducing agent, preferably IFN-β or an analog thereof.
U.S. Pat. No. 6,030,609 has previously proposed a method for treating respiratory syncytial virus (RSV) infection in the airways by aerosol delivery of IFN-β. This proposal was made solely on the basis of experiments with cultured lung epithelial cells. There is no mention in U.S. Pat. No. 6,030,609 of asthma and more particularly rhinovirus-induced exacerbation of asthma, which as indicated above is a serious clinical problem. Indeed, it is not possible to extrapolate from the experiments reported in U.S. Pat. No. 6,030,609 that IFN-β would be effective in treating rhinovirus-induced exacerbation of asthma, as RSV is known to produce proteins that interfere with Type I interferon production (Bossert & Conzelmann, Respiratory syncytial virus (RSV) nonstructural (NS) proteins as host range determinants: a chimeric bovine RSV with NS genes from human RSV is attenuated in interferon-competent bovine cells. J Virol. (2002) 76, 4287-93; and Spann et al., Suppression of the induction of alpha, beta, and lambda interferons by the NS1 and NS2 proteins of human respiratory syncytial virus in human epithelial cells and macrophages [corrected]. J Virol. (2004) April; 78(8):4363-9; Erratum in: J Virol. (2005) 78 (12):6705), whereas no similar activity is known to be produced by rhinovirus. Furthermore, although the first clinical trial in the general population using IFN-β-ser against experimental rhinovirus infection showed promising beneficial effects (Higgins P G, Al-Nakib W, Willman J, Tyrrell D A. Interferon-beta ser as prophylaxis against experimental rhinovirus infection in volunteers. J. Interferon Res. (1986) 6:153-9), in a subsequent trial for prophylaxis of natural colds, IFN-β-ser was found to be ineffective (Sperber S J, Levine P A, Sorrentino J V, Riker D K, Hayden F G, Ineffectiveness of recombinant interferon-beta serine nasal drops for prophylaxis of natural colds. J. Infect Dis. (1989) 160, 700-5), possibly because normal cells have an innate capacity to produce IFN-β in response to rhinovirus infection. As indicated above, the inventors in this instance have found that a key feature that distinguishes asthmatic epithelial cells is a deficient apoptotic response due to impaired production of IFN-β that enables viral replication to proceed unchecked, thereby contributing to prolonged symptoms and disease exacerbation. While treatment of such deficiency by use of IFN-β was first proposed by the inventors in relation to rhinovirus-induced exacerbation of asthma, it is now proposed to be equally applicable to rhinovirus-induced exacerbation of COPD, which encompasses a range of conditions including chronic bronchitis and emphysema.
As indicated above, there are also now proposed new medical uses of interferon lambda (IFN-λ). More particularly, for example, use of IFN-λ, is proposed to treat viral-induced exacerbation of respiratory disorders, especially for example, viral-induced exacerbation of asthma by viruses such as rhinovirus (RV), respiratory syncytial virus (RSV) and influenza virus. This proposal has stemmed from further investigation of interferon production in bronchial epithelial cells and bronchoalveolar lavage cells of asthmatics in response to viral infection.
One family of interferons, which includes IFN-β, are the Type I interferons. The Type I interferons are a family of closely related glycoproteins comprised of thirteen IFN-α subtypes as well as IFN-β, IFN-κ, IFN-τ and IFN-ω. The different human IFN-α subtypes have been identified by analysis of human cDNA libraries and by protein analysis of the IFNs produced by stimulated lymphoblastoid cells; the reasons for their heterogeneity remain unclear. Early studies indicated that all subtypes bind the same receptor from which it was inferred that they must elicit identical responses. Subsequently, comparative studies of both purified and recombinant subtypes revealed a spectrum of anti-viral, anti-proliferative and immunomodulatory responses.
There is one type II interferon, IFN-gamma, which binds a different receptor and has largely distinct function from the type I IFNs.
Type-I interferons are a very important component of the innate immune response to respiratory virus infection. The method of protection involves initial release of IFN-β, which then stimulates further release of IFN-β and of the IFN-αs in a cascade mediated via the type-1 interferon receptor.
The interferon-λs are three closely related proteins which have more recently-been discovered (Kotenko S. V. et al., Nature Immunology 2003; Vol 4, 69-77; Sheppard P et al., Nature Immunology 2003; Vol 4, 63-88). Interferon λ-1 is also known as IL-29, while Interferon λ-2 and 3 are known as IL-28a/b. These interferons bind a third receptor distinct from those of type I or type II interferons. Thus they are now termed the type III interferons. These interferons have been shown to have anti-viral activity in in vitro cell studies (see, for example, WO 2004/037995 of Zymogenetics Inc). However, their utility in protecting against any natural respiratory virus infection in humans has not previously been established.
In this connection, it is also worthy of note that IFN-β-ser has proved ineffective in trial for prophylaxis of natural colds despite its previously reported anti-viral activity (Sperber et al., J. Infect. Dis (1989) 160, 700-705) and that this may be explained by the capacity of normal cells to produce IFN-β in response to rhinovirus infection. Equally, it is not possible to extrapolate from in vitro studies with IFN-λ showing anti-viral activity that the same interferon type will have any therapeutic value against in vivo natural respiratory virus infection.
As indicated above, interestingly, investigation of interferon production by human asthmatic bronchial epithelial cells in response to rhinovirus infection firstly showed that such cells have a deficient type I interferon response in keeping with observed resistance to early apoptosis and increased virion production compared to RV-infected bronchial epithelial cells from healthy controls. Furthermore, provision of IFN-β to RV-infected asthmatic bronchial epithelial cells in culture was shown to cause a significant reduction in infectious virion production. These results laid the foundation for proposed new therapeutic utility of IFN-β in treating rhinovirus-induced exacerbation of asthma (Wark et al., J. Exp. Med. (21 Mar. 2005) 201, 937-947).
Further results have suggested extrapolation of use of IFN-β equally for treatment of RV-induced exacerbation of COPD, which encompasses a range of conditions, including chronic bronchitis and emphysema. COPD is a progressive disease of the airways that is characterised by a gradual loss of lung function. The symptoms of COPD include chronic cough and sputum production as well as shortness of breath. Cigarette smoking is the most common cause of COPD.
It has now been determined that IFN-λ polypeptides are strongly induced by respiratory virus infections including rhinovirus (the most common) and respiratory syncytial virus (RSV) in human cells. Example 6 and FIGS. 32 to 35 illustrate such induction in bronchial epithelial cells. Furthermore, the interferon-λs induce β and β also induces λ.
By analysing bronchial epithelial cells and bronchoalveolar lavage cells from asthmatic and normal volunteer patients, it has also now been shown that asthmatic bronchial epithelial cells are additionally deficient in IFN-λ gene expression and protein production when infected with rhinovirus. Such a finding was not previously shown or contemplated before the present invention and leads to the proposal that administering one or more IFN-λ polypeptides would also constitute an effective therapy for the treatment of viral-induced exacerbation of asthma.
Furthermore, it is suggested that equally IFN-λ polypeptides may be beneficial in the treatment of viral-induced exacerbation of other respiratory disorders such as COPD. By “respiratory disorder”, we include in addition to asthma and COPD, allergic bronchopulmonary aspergillosis, eosinophilic pneumonia, allergic bronchitis bronchiectasis, occupational asthma, reactive airayd disease syndrome, interstitial lung disease, hypereosinophilic syndrome and parasitic lung disease.